Conventionally, in game processing devices which conduct so-called "3D" image processing, whereby an object present in a virtual space is represented three-dimensionally, there have been game devices wherein the viewpoint can be switched. Here, "viewpoint" means the viewpoint from which models for playing a game (people or cars, etc.) are observed in a virtual space created for the purpose of playing the game. In terms of computer graphics, this means the viewpoint for converting to a viewpoint image system by converting the global coordinates system defining the virtual images to a field of view system.
In a game, unlike a simulator, the models operated by the players are observed from viewpoints which are generally impossible, in order to maintain operability and the excitement of the game. For example, in a baseball game, desirably, the viewpoint is not located at the actual position of the batter's eyes, but rather it is located in a position where the figure of the batter can be seen, such that the player can control the batter's actions. Furthermore, in a game featuring a car race, apart from the driver's viewpoint at the driving seat, there may also be a viewpoint which allows the whole of the car operated by the player to be seen. In other words, in many recent games, the player can select the position of the viewpoint as he or she desires.
However, in the aforementioned game processing devices, even if the viewpoint is switched, there is no change in the sound generated corresponding to the virtual image, and hence there is a lack of realism in playing the game.
Images in a game processing device are displayed three-dimensionally in order to raise the sense of realism and make the game more stimulating by basing the images provided in the game on the actual experience of the players. On the other hand, the realism of the game depends not only on the image display, but also on the high-quality sound provided corresponding to the virtual images. If realism is an important factor, then desirably, this sound should imitate the sound that the player might be expected to hear if he or she is assumed to be positioned at the viewpoint of the virtual space.
However, in conventional game processing devices, although it is possible to switch the viewpoint from which the virtual space is observed, since there is no corresponding change in the sound, there is a lack of unity between the image and the sound, and hence there is a poor sense of realism.
Furthermore, in conventional processing devices, if the viewpoint is switched, then the difficulty of the game changes. This is because the position of the viewpoint greatly affects the difficulty of the game. Namely, a viewpoint whereby it is possible to see the figure of the batter in a baseball game as described above, or the whole of a car in a car race game, makes it easier to judge, for instance, the distance to other objects in the game (objects displayed in the virtual space), and it becomes easier to comprehend the situation in which the model operated by the player is present, thus making it easier to play the game. In particular, in the case of a car race game, a viewpoint where the whole of the car can be seen is regarded as a viewpoint which makes the game relatively easier to play. On the other hand, in the case of a viewpoint which is located at the position of the driver s eyes, providing a view exactly as if the player is sitting in the driver's seat, although this has the effect of increasing the sense of realism, in fact it makes driving more difficult. Since there is a difference in operability between these games, if a game is played in correspondence with another player, then a player playing the game from a viewpoint at the driver's seat will be at a disadvantage compared to another player playing the game from a viewpoint where the whole of the car can be seen. This is because from a viewpoint at the driver's seat, it is difficult to assess the attitude of the car, for instance, if the car is sliding, or to observe others cars approaching from the rear at an early stage.
Therefore, it is necessary to make such changes in difficulty less likely to occur by providing different information to the player in response to changes in the viewpoint. In other words, if the visual information from the screen is insufficient, it is necessary to supplement this lack of information by means of sound. For this purpose, the game should be devised such that different sound effects are provided when the viewpoint is switched. If the sound effects can be changed in this way, then even if a viewpoint which is conventionally regarded as disadvantageous is selected, this disadvantage is offset by the sound, and a sense of challenge can be reintroduced into the game.